Snapshot reflection of the seasonal resilience and diversity of fungal phylotypes in the tropical Ikogosi spring.

Freshwater ecosystems like rivers, streams, and springs harbour diverse microbial communities, including fungal and bacterial phylotypes. These communities are an important part of the aquatic ecosystem, playing key roles in biogeochemical cycles. However, research on the seasonal differences concerning the fungal diversity of Ikogosi Warm Spring's sediments and water has been lacking. In this pilot study, we aimed to bridge this gap by employing high-throughput DNA sequencing to examine the fungal microbiome of this spring during the wet and dry seasons. Metagenomic DNA was extracted from water and sediment samples from different locations of the spring, and the fungal ITS1 region was sequenced using Illumina HiSeq technology. Sequences were processed with the DADA2 pipeline in R, enabling comprehensive taxonomic and diversity analyses. In addition, the spring's sediment and water physicochemical characteristics were assessed, and the impact of environmental variables on fungal communities was examined using redundancy analysis. Taxonomic analysis revealed that the spring was dominated by Ascomycota and Basidiomycota, irrespective of seasonal differences. In water samples, Ascomycota represented 62.0% (wet season) and 89.0% (dry season), while Basidiomycota accounted for 37.7% and 10.7%, respectively. Sediments exhibited a similar dominance, with Ascomycota comprising 65.1% in both seasons and Basidiomycota contributing 34.8% (wet season) and 33.5% (dry season). Alpha diversity indices indicated that fungal diversity was higher during the dry season than in the wet season, with no significant difference at p < 0.05. Redundancy analysis showed that some physicochemical factors, such as potassium and sulphate ions in water samples, were associated with seasonal patterns. These factors also influenced fungal communities in the spring, such as Cladosporium, Trichosporon, and Meyerozyma.